The goal of the parent grant is to identify susceptibility genes for Non-insulin Dependent Diabetes Mellitus (NIDDM) using a panel of large, informative families and a candidate gene linkage approach, including a specific search on chromosome 20q, a region previously identified by the U.S. and foreign investigators. The FIRCA proposal is planned to extend the parent grant by bolstering a search for the putative susceptibility gene in this critical chromosomal region. The foreign collaborator will assist in the gene search by collecting 400 discordant Polish sib-pairs and their spouses and genotyping them using 25 markers in the critical region. These markers are to be developed by the U.S. investigator. The premise of this data collection is that discordant sibpair linkage analysis can be used to narrow a region by searching for linkage disequilibrium. The investigators posit that the southeastern Polish region represents a more genetically homogeneous population that should yield a more informative result.